1. Field of the Invention
The present invention relates to a fastener and a bag having the fastener.
2. Description of the Related Art
In recent years, a bag having a fastener (zipper bag) has been used in the fields of food, medical supplies, industrial goods, and the like. The bag having the fastener includes a pair of band-shaped fasteners, which is composed of a male claw and a female claw and provided at an opening portion of a bag, so as to be freely opened and closed.
As the bag having the fastener, for example, there is a bag where a claw unit is formed between a pair of base members formed in the shape of a band, the base members are fixed to a base film used to form a bag body by thermal bonding or an adhesive, and the claw unit is opened or closed, thereby opening or closing the bag.
Meanwhile, liquid- or air-tightness is required for the bag having the fastener as one of the functions of the bag in terms of the protection of the contents. Compression bags for clothing or futons, or packaging bags with deoxidant have come into use. In recent years, bags having the fasteners, which use more expensive packaging materials having barrier properties, have come into use. The needs for bags to have fasteners, which consider liquid- or air-tightness, has significantly increased.
A fastener, which includes hook-like fitting parts engaging with each other, has been proposed in consideration of the liquid- or air-tightness. However, a general packaging bag was superior in terms of reopening/reclosing, but did not sufficiently function in terms of liquid- or air-tightness.
Accordingly, there has been proposed a fastener where a claw for providing liquid- or air-tightness and a claw having high fittability, that is, two claws are separately and independently formed to ensure high liquid- or air-tightness (for example, Patent Document 1)
[Patent Document 1] Japanese Utility Model Application No. Sho 55-117949
However, in the above-mentioned related art, two claws are separately used as the claw for providing liquid- or air-tightness and the claw having high fittability. Accordingly, it is necessary that sufficient engaging strength should be ensured in order to independently ensure the liquid- or air-tightness and high fittability. For this reason, there is a problem in that the fitted parts should be formed to have a large size and manufacturing cost is thus increased.
Further, there is a problem in that two claws need to be separately and independently opened or closed when being handled and operations are thus troublesome.
Furthermore, the fastener should have a large width in order to separately form the claw for providing liquid- or air-tightness and the claw having high fittability as described above. Accordingly, there is a problem in that a bag is subject to the limitation, such as the deterioration of the shape of a bag or the reduction of a bag manufacturing speed when a bag is manufactured.